Fainting at 21 weeks

Hey y’all!

So yesterday I woke up around 1 am with sharp all over pain in my stomach (Similar to the sensation of needing to pass gas but a bit more intense). After about 5 minutes of the pain not subsiding, I went to the bathroom though I only had to pee. The pain subsided momentarily and then came back suddenly along with strong nausea. Before even having a chance to react I woke up on the floor of the bathroom, having fainted. The pain and nausea came back as soon as I woke up, though this time I vomited. I went to the ER, where they confirmed the baby was ok, and all my tests came back regular. Though they were unsure what had happened (why I was feeling pain or why I had passed out) there was no sign of anything being wrong, so they sent me back home. I am extremely nervous now and haven’t stopped wondering what had happened and if it might happen again, as I know fainting during pregnancy is harmful to the baby (as well as my own body) Has anyone else experienced this type of thing during pregnancy or know what could have possibly caused this to occur? Any information is appreciated!!